import math
x1, y1, x2, y2 = map(float, input().split())

l = math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2)))

print('%.4f'% l) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 l = math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2))) l math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2))) math.sqrt math sqrt (math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2)) (math.fabs(x1-x2))*(math.fabs(x1-x2)) math.fabs(x1-x2) math.fabs math fabs x1-x2 x1 x2 math.fabs(x1-x2) math.fabs math fabs x1-x2 x1 x2 (math.fabs(y1-y2))*(math.fabs(y1-y2)) math.fabs(y1-y2) math.fabs math fabs y1-y2 y1 y2 math.fabs(y1-y2) math.fabs math fabs y1-y2 y1 y2 print('%.4f'% l) print '%.4f'% l '%.4f' l x2, y2 = map(float, input().split()) map(float, input().split()) x2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 l = math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2))) math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2))) l x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y2 = map(float, input().split()) map(float, input().split()) y2
import math
x1, y1, x2, y2 = map(float, input().split())

l = math.sqrt((math.fabs(x1-x2))*(math.fabs(x1-x2))+(math.fabs(y1-y2))*(math.fabs(y1-y2)))

print('%.4f'% l)